This Menstrual Health Day, we’re partnering with Period.org to celebrate periods and provide products to those in need.

Period.org is a non-profit organization started by two high school students in 2014 after realizing that menstural products are not reliably available to those who need them most. To-date they’ve supported over 250,000 periods.

From now until May 28th, for every pair of ‘Oh-No’ Proof Underwear purchased through Knixteen, $1 will be donated to Period.org.